This project is concerned with developing basic information on the ultrastructural morphology and properties of tooth enamel, using transmission and scanning electron microscopy, as well as other related physical methods. A special feature of the study is the capability of preparing thin sections of etched or fully calcified enamel for transmission electron microscopy. Objectives are to obtain a precise and detailed body of information on the basic prismatic and crystalline structures in enamel, their variations, and new information on the relation between structural organization and solubility properties. The study will also extend to investigation of pathways and damage sequence in dental caries, the effects of therapeutic agents such as fluorides, and diffusion pathways in general.